Present
theories about life on Mars suggest that if it exists it will
be microbial in nature and most probably nano-bacterial
or archaean. There is almost
no credence given to any ideas that Martian life will be any more
complex than this. Good evidence that perhaps Martian life
exists or at least, exited a long time ago has come from analysis
of Martian meteorites, as well as the
detailed examinations of the planet that have been carried out
by the series of spacecraft that have
visited.

Potentially,
Mars offers some suitable habitats for extremophile
life. In addition, there are numerous places where life
may at one time have been able to flourish. Such places
include:

Hot
springs

Dry
lake beds

Volcanic
vents

River
valleys

Ocean
basins

For
more information about the martian landscape visit the the Mars
geology page. But now let us take a closer look at some
of these particular locations.

Hot
springsOlympus Mons is the largest volcano in the Solar
System. On its south slope orbiting spacecraft have found
a hot-spot, that may indicate the presence of a hot
water springs. This may now be dry, but perhaps in
the past it was active.

Dry
lake beds

Gustav
crater resembles a dry lake bed. In this view a canyon
on its south side has been identified as a place where water
has collect. It is dry now by in the past such a place
may have supported life.

Volcanic
ventsLarge volcanoes are present on Mars, but all these are
inactive, and have been for a long time. On Earth microbes have
been found associated with undersea volcanic
vents. Similar structure may exist on Mars, but again they
may be long extinct. That does not rule out the possibility
of finding fossils or even dormant microbes in such structures.
On Earth these structures are comparatively small and the same may
be true of Mars. No definite identification of such structures
have so far been found, but they may show up, as the high resolution
images from the current and future missions are analyzed. This
image shows Arsia Mons.

River
valleysMars southern hemisphere is deeply scarred with meteorite
craters, but in the region of the Dao Vallis, a river system can
be clearly seen. This would be an ideal area to search for
fossils.

Ocean
basinsOcean basins were identified on Mars at a very early
stage in its exploration. Now, however, some doubt has been
raised about the permanence of these features on Mars. Close
up images of supposed shorelines and cliff erosion reveal no such
features. Water however certainly flowed across the surface
of Mars and formed the dry floors we see in the northern latitudes.
These now look to have been short lived incidents, with the water
quickly evaporating to space or sinking into the ground as permafrost.

There
is one place however, where something more permanent may have existed,
and that is in the bottom of the Valles Marineris, the great rift
in Mars' surface. Here a small ocean may just have existed
for something more than a fleeting moment in Mars history.